This invention relates generally to detector and alarm systems and, more particularly, to a latch and release system which is used to identify which detectors have been triggered.
There are various types of detector systems presently being marketed such as flame detectors, smoke detectors, ultraviolet detectors, unauthorized entry detectors, etc. These detectors typically provide a suitable output such as an audible signal, visible signal, or turn on a sprinkler system, etc., when a detector is activated. As described in the aforementioned co-pending application, a system has been developed where a particular action is taken, such as discharging a chemical agent to extinguish a fire, only after specific detectors are activated or a preselected number of detectors are simultaneously activated.
It is well-known that the various types of detectors, such as ultraviolet detectors, are self-resetting. This means that the detector automatically returns to its untriggered state. For example, an ultraviolet detector switches to a triggered condition only in the presence of ultraviolet light and automatically resets back to an untriggered condition in the absence of ultraviolet light. It is also known that detectors sometimes generate an intermittent or short duration spurious signal. Furthermore, battery powered detectors will often provide output signals as the battery voltage decreases due to age.
There are many situations where it is desired to have an indication of which detector was triggered even after that detector is reset. When a plurality of detectors are used in a single room or building, and each of the detectors are connected to a control panel, an audible or visible signal is usually provided to indicate when a detector is in the triggered condition. However, if the detector automatically resets, the audible signal is terminated and/or the visible signal is extinguished and hence, there is no indication of where the potential trouble exists.
Similarly, if one detector provides intermittent signals, spurious signals or signals indicating a decrease in the voltage of the power supply associated with such detector, it is desirable to have an indication of which detector provided such signals.
Prior to the present invention, it was suggested to use electrical relays for each detector so that when a detector was triggered, the actuation of the relay associated with that detector was used to energize a visible display signal which display signal had to be separately reset even after the detector returned to an untriggered condition. However, there is an extreme cost involved in providing an electrical relay for each detector in a system. In addition, in some instances, the signal from the detector was not strong enough or of sufficient duration to energize a relay.
Hence, prior to the present invention, there was no economical and satisfactory system for providing an indication of which one of several detectors had been actuated.